Stamped and welded process for making steel rectangular or square tubular parts and parts therefrom

ABSTRACT

A method of making steel square and rectangular pipe employs a die stamping operation to score steel plate and a machine to forming such parts.

This application claims the benefit from U.S. Provisional Application Ser. No. 62/351121 filed Jun. 16, 2016.

BACKGROUND OF THE INVENTION

Conventional methods for making steel pipes that become approximately square steel tube pass a preformed cylindrical tube through a series of a plurality of forming rolls (rolling mills) to gradually form a square shape steel pipe. Various considerations are taken into account with respect to the corners and weld hardness of the base material. The hardness value, therefore, it will lead to the yield strength of the corner portion and the weld portion becomes large, ductility becomes low, and during the second welding there is a danger of cracks. It takes special management, and because the mechanical properties uneven residual stress is generated, it is also difficult to carry out cutting work. The conventional method of forming steel square or rectangular shaped tubular parts and products require pre and post operations for adding additional shapes and holes. Only specific sizes and shapes can be purchased typically.

Accuracy and tolerances of features, holes and trim lines need to be greater with the current processes. Only specific sizes and shapes are typically readily available.

There remains a need to improve steel square or rectangular shaped tubular parts and the method of making the same. This instant invention solves the prior problems in the art.

SUMMARY OF INVENTION

An object of the present invention is to provide a method for producing a steel square or rectangular pipe with an improved process.

Another object of the present invention is to provide a method for producing a steel square or rectangular pipe which minimizes stress and distortion on steel material and enables forming a more accurate product.

Yet another object is to provide an improved a steel square or rectangular pipe.

Still another object to provide a less expensive steel square or rectangular pipe with ease of sizing and shaping.

Accordingly, one aspect of the invention is directed to a method of making steel square or rectangular pipe. In the case of forming a square pipe, the method includes the steps of providing a generally planar steel plate having a predetermined thickness, a front surface and a back surface, a first longitudinal edge and a second longitudinal edge, and a first transverse edge and a second transverse edge, scoring a plurality of lines longitudinally across the back surface, wherein a first longitudinal score line is a first predetermined length X from the first longitudinal edge defining a first longitudinal section, a second longitudinal score line adjacent the first longitudinal score line is the predetermined length X therefrom defining a second longitudinal section, a third longitudinal score line adjacent the second longitudinal score line is the predetermined length X therefrom defining a third longitudinal section, and also is the predetermined length X from the second longitudinal edge defining a fourth longitudinal section. The method includes applying sufficient forces on the first longitudinal section and the second longitudinal section in a manner to form approximately 90 degree bend at the first longitudinal score line and applying sufficient forces on the fourth longitudinal section and the third longitudinal section in a manner to form approximately 90 degree bend at the third longitudinal score line, applying sufficient forces on the second longitudinal section and the third longitudinal section in a manner to form approximately 90 degree bend at the second longitudinal score line thereby causing the first and second longitudinal edges to abut. The method further includes applying a weld on the the first and second longitudinal edges to form a square steel pipe.

In the case of forming rectangular steel tube, the method includes the steps of providing a generally planar steel plate having a predetermined thickness, a front surface and a back surface, a first longitudinal edge and a second longitudinal edge, and a first transverse edge and a second transverse edge, scoring a plurality of lines longitudinally across the back surface, wherein a first longitudinal score line is a first predetermined length X from the first longitudinal edge defining a first longitudinal section, a second longitudinal score line adjacent the first longitudinal score line is a second predetermined length Y from the first longitudinal score line defining a second longitudinal section, a third longitudinal score line adjacent the second longitudinal score line is a second predetermined length 2X from the second longitudinal score line defining a third longitudinal section, and a fourth longitudinal score line adjacent the third longitudinal score line is the predetermined length Y defining a fourth longitudinal section and the fourth longitudinal score line is the predetermined length X from the second longitudinal edge defining a fifth longitudinal section. The method includes applying sufficient forces on the first longitudinal section and the second longitudinal section in a manner to form an approximately 90 degree bend at the first longitudinal score line and applying sufficient forces on the fifth longitudinal section and the fourth longitudinal section in a manner to form an approximately 90 degree bend at the fourth longitudinal score line. The method further includes applying sufficient forces on the second longitudinal section and the third longitudinal section in a manner to form approximately 90 degree bend at the second longitudinal score line and applying sufficient forces on the third longitudinal section and the fourth longitudinal section in a manner to form approximately 90 degree bend at the third longitudinal score line thereby causing the first and second longitudinal edges to abut. The method further includes applying a weld on the the first and second longitudinal edges to form a rectangular steel pipe.

The method can provide score lines by way of a stamping tool. The tool can also include a die tool face to provide the score lines and optionally other desired features in the pipe, such open surfaces in one or more of the longitudinal sections which can be coaxial aligned, for example.

A steel pipe is provided which includes a steel plate formed with at least four sides of equal length and having opposing sections of equal width wherein all sides have a predetermined thickness, including two outermost sections welded together at a respective outermost edge thereof, and each remaining section integrally connecting to another section generally at a 90 degree bend and having a scoring line internally formed longitudinally across an internal surface which serves to impart the 90 degree bend.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of forming a square steel pipe of the instant invention.

FIG. 2A is a schematic of forming a rectangular steel pipe of the instant invention.

FIG. 2B is another schematic of forming a rectangular steel pipe of the instant invention.

FIG. 3 is a schematic of a stamping mechanism to form the steel pipe of the instant invention.

FIG. 4 is an exploded view of a part of FIG. 3.

FIG. 5 shows a plate of the invention with score lines for forming a square pipe.

FIG. 6A shows another plate of the invention with score lines for forming a rectangular pipe.

FIG. 6B shows still another plate of the invention with score lines for forming a rectangular pipe.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, the process and method of forming the steel square or rectangular shaped tubular pipe of the invention is generally referred to by the numeral 10, wherein like parts include like numerals. The invention provides a stamping tool 12 having s plurality of precision formed cutting/scoring die faces 14 that score or cut and form score lines 18 on steel plate 20 into a desired shape or profile. The die face 14 is made from hardenable tool steel and contain cutting and forming sections made from carbide or various other hard, wear-resistant materials.

The stamping tool 12 can include one or more angle forming members 16 having a male angled V-shaped face 17 having a leading edge 21 and female angle V-shaped face 19 providing a seat between which the plate 20 is placed in a manner such that a score line 18 aligns with the leading edge 21 of each male angled V-shaped face 17. In the case of forming the rectangular pipe 150, there are provided opposing cams 23 and 25 bearing against sides 136B and 136D which cause opposing sections (e.g., 136A, 136E) of plate 20 to overlap and spring back to a 90 degree angle as a function of the material strength and memory. In this regard, a drive hump 27 is provided to drive one free section (e.g., 136E) under another free section (e.g., 136A).

Generally speaking, the invention is performed using metal stamping tool 12 to form the shape of the pipe 50, 150 along with features, and holes, providing a weld fixture and equipment to form the weld seam on the pipe 50, 150 as will be discussed and providing sanding and polishing equipment as needed for the pipe 50, 150 to grind/sand the weld seam flush with a wall of the pipe 50, 150.

A method of making steel square pipe 50 is provided. In the case of forming a square pipe 50 as in FIG. 1, the method includes the following steps. Step one is to provide a generally planar and rectangular or square steel plate 20 having a predetermined thickness, a front surface 22 and a back surface 24, a first longitudinal edge 26 and a second longitudinal edge 28, and a first transverse edge 30 and a second transverse edge 32. Step two is to provide scoring a plurality of lines 34 longitudinally across the back surface 24, wherein a first longitudinal score line 34A is a first predetermined length X from the first longitudinal edge 24 defining a first longitudinal section 36A, a second longitudinal score line 34B adjacent and parallel the first longitudinal score line 34A is the predetermined length X therefrom defining a second longitudinal section 36B, a third longitudinal score line 34C adjacent and parallel the second longitudinal score line is the predetermined length X therefrom defining a third longitudinal section 36C, and also is the predetermined length X from the second longitudinal edge 28 defining a fourth longitudinal section 36D. Step three includes applying sufficient forces on the first longitudinal section 36A and the second longitudinal section 36B in a manner to form approximately 90 degree bend at the first longitudinal score line 34A and applying sufficient forces on the fourth longitudinal section 36D and the third longitudinal section 36C in a manner to form approximately 90 degree bend at the third longitudinal score line 34C, applying sufficient forces on the second longitudinal section 36B and the third longitudinal section 36C in a manner to form approximately 90 degree bend at the second longitudinal score line 34B thereby causing the first and second longitudinal edges 26 and 28 to abut. Step 3 can also include over bending two opposing longitudinal sections (e.g., 36A and 36C) such that the first and second longitudinal edges 26 and 28 temporarily overlap prior to springing back to abutted position. A cam mechanism as described below can be used in this regard. Step 4 includes applying a weld surface 40 on the first and second longitudinal edges 26 and 28 to form square steel pipe 50. The method can include smoothing the weld surface 40.

FIGS. 2A and 2B provide exemplary methods for forming rectangular steel tube 150 showing width variations, wherein the method includes the following steps. Step one is providing a generally square or rectangular planar steel plate 120 having a predetermined thickness, a front surface 122 and a back surface 124, a first longitudinal edge 126 and a second longitudinal edge 128, and a first transverse edge 130 and a second transverse edge 132. Step two includes scoring a plurality of lines 134 longitudinally across the back surface 124, wherein a first longitudinal score line 134A is a first predetermined length X from the first longitudinal edge 126 defining first longitudinal section 136A, a second longitudinal score line 134A adjacent and parallel the first longitudinal score line 134A is a second predetermined length Y therefrom defining second longitudinal section 136B, a third longitudinal score line 134C adjacent and parallel the second longitudinal score line 134B is a second predetermined length 2X therefrom defining third longitudinal section 136C, and a fourth longitudinal score line 134D adjacent and parallel the third longitudinal score line 134C is the predetermined length Y therefrom defining fourth longitudinal section 136D and the fourth longitudinal score line 134D is the predetermined length X from the second longitudinal edge 128 defining fifth longitudinal section 136E. Step 3 includes applying sufficient forces on the first longitudinal section 136A and the second longitudinal section 136B in a manner to form an approximately 90 degree bend at the first longitudinal score line and applying sufficient forces on the fifth longitudinal section 136E and the fourth longitudinal section 136D in a manner to form an approximately 90 degree bend at the fourth longitudinal score line 134D, and further includes applying sufficient forces on the second longitudinal section 136B and the third longitudinal section 136C in a manner to form approximately 90 degree bend at the second longitudinal score line 134B and applying sufficient forces on the third longitudinal section 136C and the fourth longitudinal section 136D in a manner to form approximately 90 degree bend at the third longitudinal score line 134C thereby causing the first and second longitudinal edges 126 and 128 to abut. This step can include over bending two opposing longitudinal sections (e.g., 136B and 136D relative to 136C) using the drive hump 27 and cams 23 and 25 such that the first and second longitudinal edges 126 and 128 temporarily overlap prior to springing back to abutted position. The method further includes applying a weld surface 140 on the first and second longitudinal edges 126 and 128 to form rectangular steel pipe 150. The method can include smoothing the weld surface 140.

The method can provide score lines by way of stamping tool 12 having tool die tool face 14 to provide the score lines and optionally other desired features in the pipe 50, 150 to form open surfaces in one or more of the longitudinal sections 36, 136 wherein such open surfaces can be coaxial aligned, for example. Steel square and rectangular tubular parts can be manufactured with specific holes, shapes and features in a stamped production process with no or less secondary processes. The die face 14 is configured to score all said scoring lines at once and can be removable to provide such features as required.

The stamping process for making the pip 50, 150 allows added holes, shapes and features to be incorporated as needed. The weld process can accommodate the finished tubular product by welding only as needed. The sanding/polishing process is used as needed to finish or smooth the exterior of the pipe 50, 150 as needed.

The invention provides for manufacture of any metal square or rectangular parts. This invention allows steel tubular parts to be manufactured with more detail, less cost and processes, consistent quality, more options for steel types, and more options for sizes of tubing. It minimizes costs and operations for making steel rectangular and square products and assemblies. It allows the ability to minimize the amount of parts to make a product or assembly. It allows the use of different steel types and sizes of shapes.

Prior steel square or rectangular shaped tubular parts and products typically made with rolling mills which require pre and post operations for adding additional shapes and holes. Only specific sizes and shapes can be purchased typically. The instant invention solves this problem and provides for more options for sizes and shapes and openings to be formed at reduced cost.

Further, in the process of roll milling steel tubular shapes, the metal is stretched and compressed requiring tolerances on the finished product to be increased. The instant invention solves this problem and minimizes the stresses and distortion on the material and makes for a more accurate product.

It is to be understood that numerous additions, modifications, and derivations may be made to the present invention which fall within the intended scope of the above description and the claims appended hereto should be afforded the scope of such additions, modifications, and derivations. The configuration and construction materials used in connection with the invention may be modified or changed so long as the intended functionality is neither degraded nor destroyed. There has therefore been shown and described a method of making square and rectangular steel parts which accomplishes at least all of its intended objectives. 

What is claimed is:
 1. A method of making steel square pipe includes the steps of: providing a generally planar steel plate with equal length opposing sides and having a predetermined thickness, a front surface and a back surface, a first longitudinal edge and a second longitudinal edge, and a first transverse edge and a second transverse edge; scoring a plurality of lines longitudinally across the back surface, wherein a first longitudinal score line is a first predetermined length X from the first longitudinal edge defining a first longitudinal section, a second longitudinal score line adjacent and parallel the first longitudinal score line is the predetermined length X therefrom defining a second longitudinal section, a third longitudinal score line adjacent and parallel the second longitudinal score line is the predetermined length X therefrom defining a third longitudinal section, and also is the predetermined length X from the second longitudinal edge defining a fourth longitudinal section; and applying sufficient forces on the first longitudinal section and the second longitudinal section in a manner to form approximately 90 degree bend at the first longitudinal score line and applying sufficient forces on the fourth longitudinal section and the third longitudinal section in a manner to form approximately 90 degree bend at the third longitudinal score line, applying sufficient forces on the second longitudinal section and the third longitudinal section in a manner to form approximately 90 degree bend at the second longitudinal score line thereby causing the first and second longitudinal edges to abut to form square steel pipe.
 2. The method of making steel square pipe of claim 1, which includes applying a weld surface on the first and second longitudinal edges. The method can include smoothing the weld surface.
 3. The method of making steel square pipe of claim 2, which includes smoothing the weld surface.
 4. The method of making steel square pipe of claim 1, which includes employing a stamping tool having a die face configured to score all said scoring lines at once.
 5. The method of making steel square pipe of claim 4, wherein said die face further includes a tool surface for making at least one opening in at least one said longitudinal section.
 6. The method of making steel square pipe of claim 5, wherein said die face further includes at least two tool surface for making at least two opening in at least two said longitudinal sections.
 7. The method of making steel square pipe of claim 6, which is further characterized such that said die face further two tool surface are configured for making at least two coaxially aligned openings in at least two said longitudinal sections.
 8. A method of making steel rectangular pipe includes the steps of: providing a generally planar steel plate with equal length opposing sides and having a predetermined thickness, a front surface and a back surface, a first longitudinal edge and a second longitudinal edge, and a first transverse edge and a second transverse edge; scoring a plurality of lines longitudinally across the back surface, wherein a first longitudinal score line is a first predetermined length X from the first longitudinal edge defining a first longitudinal section, a second longitudinal score line adjacent and parallel the first longitudinal score line is a second predetermined length Y therefrom defining a second longitudinal section, a third longitudinal score line adjacent and parallel the second longitudinal score line is a second predetermined length 2X therefrom defining a third longitudinal section, and a fourth longitudinal score line adjacent and parallel the third longitudinal score line is the predetermined length Y therefrom defining a fourth longitudinal section and the fourth longitudinal score line is the predetermined length X from the second longitudinal edge 128 defining a fifth longitudinal section; applying sufficient forces on the first longitudinal section and the second longitudinal section in a manner to form an approximately 90 degree bend at the first longitudinal score line and applying sufficient forces on the fifth longitudinal section and the fourth longitudinal section in a manner to form an approximately 90 degree bend at the fourth longitudinal score line, and further includes applying sufficient forces on the second longitudinal section and the third longitudinal section in a manner to form approximately 90 degree bend at the second longitudinal score line and applying sufficient forces on the third longitudinal section and the fourth longitudinal section in a manner to form approximately 90 degree bend at the third longitudinal score line thereby causing the first and second longitudinal edges and to abut to form a rectangular pipe.
 9. The method of making steel square pipe of claim 8, which includes applying a weld surface on the first and second longitudinal edges. The method can include smoothing the weld surface.
 10. The method of making steel square pipe of claim 9, which includes smoothing the weld surface.
 11. The method of making steel square pipe of claim 9, which includes employing a stamping tool having a die face configured to score all said scoring lines at once.
 12. The method of making steel square pipe of claim 11, wherein said die face further includes a tool surface for making at least one opening in at least one said longitudinal section.
 13. The method of making steel square pipe of claim 12, wherein said die face further includes at least two tool surface for making at least two opening in at least two said longitudinal sections.
 14. The method of making steel square pipe of claim 13, which is further characterized such that said die face further two tool surface are configured for making at least two coaxially aligned openings in at least two said longitudinal sections.
 15. A steel pipe, which includes a steel plate formed with at least four sides of equal length and having opposing sections of equal width wherein all sides have a predetermined thickness, including two outermost sections welded together at a respective outermost edge thereof, and each remaining section integrally connecting to another section generally at a 90 degree bend and having a scoring line internally formed longitudinally across an internal surface which serves to impart said 90 degree bend. 